Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define int long long
typedef pair<int,int> P;
int n,m;
char a[55][55];
int f[111][111];
int black;
int dx[]={1,0,-1,0};
int dy[]={0,-1,0,1};
signed main(){
	cin>>n>>m;
	rep(i,n)rep(j,m){
		cin>>a[i][j];
		black+=(a[i][j]=='#');
		f[i][j]=1145141919;
	}
	queue<P>q;
	q.push({0,0});
	f[0][0]=0;
	while(!q.empty()){
		P p=q.front();
		q.pop();
		rep(i,4){
			int x=p.first+dx[i];
			int y=p.second+dy[i];
			if(x<0||x>=n||y<0||y>=m||a[x][y]=='#')continue;
			if(f[x][y]>f[p.first][p.second]+1){
				f[x][y]=f[p.first][p.second]+1;
				q.push({x,y});
			}
		}
	}
	if(f[n-1][m-1]==1145141919)puts("-1");
	else cout<<n*m-f[n-1][m-1]-black-1<<endl;
	return 0;
}